Cases like that I refer to as OC's wearing a known character's skin. They are in no way actually the character they supposedly represent. It's crap like that that makes me never read or look at other peoples work cuz half of them wouldn't know that person's personality and mannerisms if that character taught a class him/herself.
I have to admit, that I have no problem with ... tweaking ... a character a bit as long as they don't put it into a blender and press start. The character should be at least recognizable.
I think the younger a character the more possibilities there are to what one can do with them. Byakuya is a prime example that there can be rather stunning changes as one grows up. In those cases it's the core personality that counts. For example: I cannot simply take someone like Orihime and make her kill someone in cold blood. That would be like Kenpachi becomming a pacifist. There are certain things that just haver to be constant.
Other aspects aren't as set. I see no problem with someone writing a Ichigo yaoi. Sure, there is nothing in the series supporting such a development, but then again ... he is only what? 15? That's really young. Nobody knows anything for certain at that age. I certainly didn't.
Well, but that's all just my opinion. And I can understand, if you are a bit stricter then me. After all, not only fictional characters have to stay true to themself. XD
You know that flippy feeling you get in ur stomach when something so heartfelt just happened(i usually get those when I'm reading a good romance book) you nailed it!!!! i got the stomach flippy!! awesome!!